The invention provides a filter for a hemodialysis circuit device, which comprises a first cover and a second cover. The first cover has a flange structure, and the second cover has a groove corresponding to the shape of the flange structure, so that the second cover is connected with the flange structure of the first cover to form the filter.The groove and the surface of one of the flange structures have at least one convex part, and the groove and the surface of the other of the flange structure have at least one pair of concave parts corresponding to the convex part.Therefore, the invention can improve the joint strength of the first cover and the second cover after the first cover and the second cover are welded by ultrasonic welding.本創作係提供一種過濾器，用於血液透析迴路裝置，該過濾器包含第一蓋件及第二蓋件，該第一蓋件具有凸緣結構，該第二蓋件具有對應該凸緣結構之外形的凹槽，俾使該第二蓋件藉由該凹槽與該第一蓋件之凸緣結構接合而形成該過濾器。本創作之該凹槽與該凸緣結構之其中一者的表面具有至少一凸部，且該凹槽與該凸緣結構之另一者的表面具有至少一對應該凸部之凹部。據此，本創作過濾器能在第一蓋件與第二蓋件以超音波焊接方式接合後，提高第一蓋件及第二蓋件的接合強度。
